Hitherto, there have been used various types of airbag devices, which serve to restrain the body of an occupant in an event of a vehicle collision or the like, such as a driver airbag device that is inflated and extends to the side of a driver from the rotation center of a steering wheel in a driver seat, a passenger airbag that is inflated and extends to the side of a passenger seat from an instrument panel, and the like.
In recent years, airbag devices have been proposed that are applicable to a possible case such that an occupant suffers an impact on his/her head from overhead due to a shock of an eventual big accident, which applies a large force to an automobile, such as a lateral overturn of a vehicle body caused by a collision or the like, a drop of a heavy body like a falling tree, or the like (for example, refer to Patent Document 1).
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-37011